1. Technical Field
The present invention relates generally to a shipping and display carton. More specifically, the invention relates to a shipping carton, and a method of making a shipping carton, that is easily transformed into a display carton having neatly severed walls.
2. Description of Related Art
Millions of dollars are spent each year in packaging products for transportation from the manufacturer to the store. Rather than require these products to be removed from the container and individually placed on shelves, it has long been desirable to ship products in cartons that can quickly be converted to provide a display format. Because of the variety of products and their differing needs, many different types of shipping and display cartons have been made. Examples of combination shipping and display cartons can be found in U.S. Pat. No. 2,152,079 to Mott, U.S. Pat. No. 3,315,875 to Praetorius, U.S. Pat. No. 4,000,811 to Hardison et al., and U.S. Pat. No. 5,826,728 to Sheffer, to name a few, all of which are incorporated by reference. Each of these patents attempts to provide a convertible carton that will provide adequate protection for its contents during shipping, then transform into an aesthetic display carton.
By far the most common material used for shipping/display cartons is corrugated cardboard. This material is strong, lightweight, relatively inexpensive, and recyclable. When converting a corrugated shipping carton into a display carton, it would be desirable to have a carton that is easy to open, yet presents a pleasing appearance without inadvertent tears. Several means already exist that attempt to achieve this goal, although all have drawbacks. These drawbacks will be further explained using an exemplary carton, shown in FIG. 1a. 
FIG. 1A shows a prior art design for a shipping and display carton 100 that has the shape of a rectangular prism measuring about 9¼×19½×9½ inches. The carton has four solid sides: top and bottom panels 110 and two end panels 120. Two short flaps 130 extend from the end panels 120 and two long flaps 140 extend from top and bottom panels 110. The two long flaps 140 are sized so that they do not meet to completely close the box; rather, all the flaps 130, 140 together frame an opening 150 in the carton, with overlapping flaps 130, 140 in each corner. Tape can be wrapped from the long flaps 140 to the ends 120 to seal and stabilize the carton, or the overlapping flaps 130, 140 can be glued or otherwise fastened together to seal the carton. This carton design is used for shipping lightweight containers of snack foods, such as chips. To convert the carton to display, the stocker removes the top half or two-thirds of the carton by cutting a line completely across each of the short flaps 130 and end panels 120. This creates a tray 150 having short edges that hold the product in place yet provide high visibility to consumers. FIG. 1B presents an idealized conversion to a display carton 100′ with perfectly straight edges that neatly bisect panels 120 and 130 to create shortened sides 120′ and 130′. The ability to make this neat of a transformation is desirable, but rarely obtainable. Often, the person stocking the product is in a hurry, so the actual cuts are rarely this straight or this neat. Further, the stocker must carry a knife and must take care not to cut the product during the process of converting the carton to display. In other carton designs, extra layers of cardboard are sometime included beneath the cut lines; these layers are used to protect the product during cutting, but add to the expense.
One alternative to cutting the carton is to use special tear strip tapes, such as those offered by 3M Corporation. These tapes can be used to make an easy-to-open carton that has a neat appearance, but they add significantly to the cost of the carton.
A third alternative is to provide perforations in the cardboard itself, so that sections of the carton can be quickly removed for display. This method is inexpensive, but has problems of its own. FIGS. 2a and 2b are taken from U.S. Pat. No. 3,315,875 to Praetorius and demonstrate a prior art method of turning a shipping carton 200 into a display carton 200′. Perforated lines 202 make a U-shape, defining a removable strip 204 that includes the larger flap 206 of the lid. Additional perforated lines 208 allow the smaller flaps 210 to be removed, creating the open display carton 200′. However, it can be difficult to obtain a clean tear. This is especially true at the edges of the carton, where the tear has to turn a corner. The strength of the cardboard is enhanced by the adjacent wall, so additional force is needed to tear. At the same time, the direction of the force needs to change abruptly; it is difficult to provide the extra force in a controllable manner. Too often tearing across a corner results in ragged edges that are less appealing. Additionally, the perforations create weakened sections of the carton that can accidentally tear, often when the package is being assembled. The carton of FIG. 2a is exemplary of this. When the blank is being folded to form the carton, care must be taken when making the vertical folds 212; otherwise the cardboard may accidentally fold along the weakened line of perforations 202, further weakening the line of perforations 202 and causing premature tearing. Likewise, the folds at the base of flaps 210 are weakened by the perforated lines 208. The pre-mature removal of the flaps 210 would leave a gap in the shipping carton 200. Because of these problems, this method has thus far proved to be inexpensive but less than ideal.
Consequently, it would be desirable to have a carton that is easily convertible from a shipping carton to a display carton, presents a neat, pleasing appearance for display, does not tear prematurely, requires no tools, and adds little or nothing to the cost of making the carton.